In an image forming apparatus such as a photocopier, printer, facsimile and multi-functional peripheral wherein an image is formed based on image data, a document is exposed to an exposure lamp to read the reflected light, and an image data is generated. Based on this image data, an electrostatic latent image is formed on a photoconductor drum or the like by a writing unit using laser light. This electrostatic latent image is developed by the development unit containing toner and developer, and is transferred directly or through a transfer belt onto the sheet supplied by a sheet feed roller. After that, the toner is fixed onto the sheet by the pressure and heat applied by a fixer.
The approximate service life of the aforementioned parts such as photoreceptor drum, development unit, sheet feed roller, transfer belt, and fixing device are determined by the number of uses. These parts are designed to be replaceable, and are replaced at appropriate intervals, whereby high image quality can be maintained. In the conventional method, replacement, maintenance and inspection of these parts and units have been taken care of exclusively by a serviceman familiar with the structure of the apparatus. In the recent digital printing industry, replacement of the aforementioned parts can be performed quickly by an operator handling the apparatus, without having to wait for the dispatch of a serviceman.
Incidentally, to allow the maintenance, inspection and replacement of the parts to be performed, the image forming apparatus is provided with an open/close-type door. This open/close-type door is normally closed. Only when the aforementioned work is to be performed, the open/close-type door is opened to perform the work. The main body of such an apparatus incorporates a charging device that operates at a high voltage and a fixing device being heated to a high temperature. If these devices are kept operating with the open/close-type door open, working safety will not be ensured. Thus, the conventional image forming apparatus is provided with an interlock switch that operates in synchronism with the opening and closing of the door. When the door is opened, the power of the apparatus is automatically turned off by the interlock switch. When the open/close-type door has been closed, power supply is started to allow the operation to be performed (Unexamined Japanese Patent Application Publication No. Sho 62 (1987)-69277).
Generally, operators have a lower level of skill than servicemen. It is preferred that operators confirm the replacement work procedure during the replacement work. However, in the conventional image forming apparatus, at the time of parts replacement, the apparatus power is turned off by opening the open/close-type door. This makes it necessary to use a label or manual as instructions for the parts replacement procedure. When the parts replacement procedure is complicated particularly in the parts replacement work of a sophisticated large-sized apparatus, it is very difficult to instruct the operator on the details of the replacement procedure. Another problem is that, in the conventional image forming apparatus, the power of the apparatus is turned off in the replacement mode. Thus, the apparatus itself is incapable of determining if the parts have been replaced or not. This fails to notify the operator of the replacement on a real-time basis. Thus, in cases wherein the operator closes the door or turns on power without the parts and others having been completely replaced, the initial operation of the apparatus starts as the power is turned on, and the machine may be seriously damaged due to incomplete replacement. In the conventional art, there is an increase in the aforementioned risk because the replacement work having been done by the serviceman alone is released to the operator.
In view of the problems described above, it is an object of the present invention to provide an apparatus for ensuring safety and reliable replacement work to be performed in cases wherein the parts and units of the apparatus are replaced by an operator.